A storage system includes a channel interface (IF) unit having an interface with a server, a disk IF unit having an interface with a hard disk group, a memory unit for storing data to be read/written from/to the server or the hard disk group, a switching unit, and the hard disk group. The channel IF unit, the disk IF unit, and the memory unit are connected to each other through the switching unit, and an encryption and decryption processing unit is provided between a host IF unit and a transfer controller in the channel IF unit.